Internal combustion engines produce exhaust gases containing a variety of pollutants, including hydrocarbons, carbon monoxide, nitrogen oxides, sulfur oxides, and particulate matter. Increasingly stringent national and regional legislation has lowered the amount of pollutants that can be emitted from such internal combustion engines. Many different techniques have been applied to exhaust systems to clean the exhaust gas before it is emitted to the atmosphere.
One proposed method for cleaning exhaust gases utilizes a catalytic reforming process. See for example SAE-07NAPLES-175 which teaches on board exhaust gas reforming of gasoline using a combined reformer and a three-way catalyst. U.S. Patent Application Publication No. 2012/0117943 also teaches an on board gas reforming system.
It is believed that a lower amount of emitted pollutants can be achieved by including hydrogen, from the catalytic reformer, in the fuel to the internal combustion engine. For instance, it has been suggested that diesel or gasoline fuel may be reformed to produce hydrogen, and that the hydrogen may be added back to the fuel fed to the engine in order to directly reduce NOx and particulate emissions from the engine. Further, there is also current interest in reforming because of the potential for recovery of energy (i.e., combustion heat) in the exhaust by conversion of exhaust components into fuel components of higher calorific value (H2 and CO). This could permit an increase in overall efficiency of a gasoline engine and an associated decrease in fuel consumption and a decrease in CO2 emissions.
As with any automotive system and process, it is desirable to attain still further improvements in exhaust gas treatment systems, particularly those systems that utilize catalytic reforming. We have discovered a new exhaust system utilizing a fuel reformer catalyst.